linux/crypto/dh_helper.c
<<
>>
Prefs
   1/*
   2 * Copyright (c) 2016, Intel Corporation
   3 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public Licence
   7 * as published by the Free Software Foundation; either version
   8 * 2 of the Licence, or (at your option) any later version.
   9 */
  10#include <linux/kernel.h>
  11#include <linux/export.h>
  12#include <linux/err.h>
  13#include <linux/string.h>
  14#include <crypto/dh.h>
  15#include <crypto/kpp.h>
  16
  17#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int))
  18
  19static inline u8 *dh_pack_data(void *dst, const void *src, size_t size)
  20{
  21        memcpy(dst, src, size);
  22        return dst + size;
  23}
  24
  25static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size)
  26{
  27        memcpy(dst, src, size);
  28        return src + size;
  29}
  30
  31static inline int dh_data_size(const struct dh *p)
  32{
  33        return p->key_size + p->p_size + p->g_size;
  34}
  35
  36int crypto_dh_key_len(const struct dh *p)
  37{
  38        return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p);
  39}
  40EXPORT_SYMBOL_GPL(crypto_dh_key_len);
  41
  42int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
  43{
  44        u8 *ptr = buf;
  45        struct kpp_secret secret = {
  46                .type = CRYPTO_KPP_SECRET_TYPE_DH,
  47                .len = len
  48        };
  49
  50        if (unlikely(!buf))
  51                return -EINVAL;
  52
  53        if (len != crypto_dh_key_len(params))
  54                return -EINVAL;
  55
  56        ptr = dh_pack_data(ptr, &secret, sizeof(secret));
  57        ptr = dh_pack_data(ptr, &params->key_size, sizeof(params->key_size));
  58        ptr = dh_pack_data(ptr, &params->p_size, sizeof(params->p_size));
  59        ptr = dh_pack_data(ptr, &params->g_size, sizeof(params->g_size));
  60        ptr = dh_pack_data(ptr, params->key, params->key_size);
  61        ptr = dh_pack_data(ptr, params->p, params->p_size);
  62        dh_pack_data(ptr, params->g, params->g_size);
  63
  64        return 0;
  65}
  66EXPORT_SYMBOL_GPL(crypto_dh_encode_key);
  67
  68int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
  69{
  70        const u8 *ptr = buf;
  71        struct kpp_secret secret;
  72
  73        if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE))
  74                return -EINVAL;
  75
  76        ptr = dh_unpack_data(&secret, ptr, sizeof(secret));
  77        if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH)
  78                return -EINVAL;
  79
  80        ptr = dh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
  81        ptr = dh_unpack_data(&params->p_size, ptr, sizeof(params->p_size));
  82        ptr = dh_unpack_data(&params->g_size, ptr, sizeof(params->g_size));
  83        if (secret.len != crypto_dh_key_len(params))
  84                return -EINVAL;
  85
  86        /* Don't allocate memory. Set pointers to data within
  87         * the given buffer
  88         */
  89        params->key = (void *)ptr;
  90        params->p = (void *)(ptr + params->key_size);
  91        params->g = (void *)(ptr + params->key_size + params->p_size);
  92
  93        return 0;
  94}
  95EXPORT_SYMBOL_GPL(crypto_dh_decode_key);
  96